see article/footer.tpl:
examples:
alt="Bookmark and Share"
style="border:0;padding:0"
title="Bookmark using any bookmark manager!"
strings should be translated and styles should be managed via CSS only

Some other less than optimal implementation issues IMO:
- SharingRT::getLanguages() contains a hard coded language list. This should probably go to Locale or some other library class unless this list is somehow restricted by "share-this".
- SharingRT::getBtnStyles() contains information that belongs into the view and should be held somewhere there (image names, image pixel width and height).
- both methods are not properly documented.
- If we had a CSS-styled button with a background image then we probably wouldn't need translated images at all which would make maintenance of this RT much easier.

(In reply to comment #1)
> - SharingRT::getLanguages() contains a hard coded language list. This should
> probably go to Locale or some other library class unless this list is somehow
> restricted by "share-this".
PKPLocale now contains conversion methods (see #5983) that take a locale to an iso 3-letter code (and vice-versa) and that convert between iso 2- and 3-letter codes for languages. Use these methods rather than SharingRT::getLanguages().